单分散聚芴熔融结晶形态

共轭高分子以其优异的性能在有机电子器件领域表现出了极大的应用前景。大量研究表明器件性能与薄膜凝聚态结构息息相关。特别是对于有机薄膜晶体管（OTFTs）和有机光伏电池（OPVs）来说，大面积连续的高结晶性薄膜往往会带来好的器件性能。由于高分子分级结晶行为的影响，高分子的多分散性会显著影响薄膜的结晶性。鉴于此，本论文以一种得到广泛研究的共轭高分子——聚芴（PFO）作为研究对象，选取三种不同分子量的单分散聚芴，通过熔融结晶的方法来制备大面积连续的高结晶性薄膜，系统性的研究了单分散聚芴的热结晶行为、晶体相结构及其光物理性质，并研究分子量对于聚芴结晶的影响，总结了聚芴的熔融结晶规律，给出了不同分子量聚芴相图。本论文主要研究成果如下： 1. 对于十六聚体聚芴（F16），直接从溶液中滴涂得到的为含β相的薄膜，薄膜保有部分F16针状单晶的形貌。通过两步热退火得到了片层状晶体，为一种新相（β’相）。其属于正交晶系Pmc21空间群，晶胞参数为 a = 1.30 nm, b = 2.22 nm, c = 3.36 nm。晶胞含有4条链，密度为1.06 g/cm3。片晶中分子主链平行于片层平面，烷基侧链垂直于片层。通过熔融结晶的方法得到了球晶，球晶也是β’相，由片晶组成，球晶内分子链平行于半径方向，烷基侧链垂直于基底。与β相相比，β’相为F16的热力学稳定相。 2. 对于三十二聚体（F32）和六十四聚体（F64）聚芴，直接从溶液中滴涂得到含β相的无规薄膜。 通过熔融结晶的方法得到了大面积连续的纳米纤维晶薄膜。结晶薄膜保有部分液晶薄膜的织构特点。薄膜内部存在片层结构。薄膜结晶过程为从晶核开始的辐射生长，最终形成球晶状结构，并且球晶边界处有一定程度的相互融合。结晶薄膜为α相，其晶胞参数为a=2.60 nm、b=2.38 nm和c=3.32 nm。与β相相比，α相为F32和F64的热力学稳定相。 3. 在F32与F64 α相纳米纤维薄膜中，分子链平行于纤维宽度方向，芴环堆积方向为纤维长轴方向。F32与F64分子在纳米纤维晶中为伸直链构象。 4. 通过对以上工作的总结，我们得到了不同链长聚芴相图。发现分子链长可以影响聚芴熔融结晶相，对于F16得到的为β’相，对于F32和F64得到的为α相。通过两相形貌图的对比，我们总结出了聚芴熔融结晶的规律。F16倾向于表现小分子的结晶特点，形成的是典型的片层状晶体；F32与F64表现出了高分子的结晶特点，形成的是纳米纤维晶薄膜，但薄膜仍表现出了层状结构特点。并且我们推测这种链长对相的影响和片层状结构在其他高分子体系中也会出现。Conjugated polymers have great application prospect due to the high performance in organic electronic devices fields. Mounts of studies have demonstrated that the devices performance is highly relative with the condensed structure of films. Especially for organic thin film transistors (OTFTs) and organic photovolatics (OPVs), large-area continuous highly crystalline films can produce high device performance. Because of the influence of the fractionated crystalline behaviour of conjugated polymers, the polydispersity of polymers vastly hinders the increasing of film crystallinity. With this motivation, a widely-used conjugated polymers – Poly(9,9-diotclyfluorene) (PFO) was chosen as the studied object in this dissertation. We selected three monodisperse PFO with different molecular weights. Large-area continuous highly crystalline films were prepared by melt crystallization. Moreover, the thermal-crystalline behaviour, phase structure and photophysical property of monodisperse PFO were systematically investigated. Besides, we also investigated the effect of molecular weights on PFO crystallization. The melt-crystalline discipline of PFO was summarized, and the phase diagram of monodisperse PFO with different molecular weights was given. The main results of this dissertation are as follows: 1. For monodisperse PFO with 16 repeating units (F16), thin films containing β phase were prepared by directly dropping from solution, and the films preserve some of shape of needle-like single crystal prepared by solution crystallization of F16. Lamellar crystals, which is a novel phase (named as β’ phase), were prepared by two-step thermal annealing. The β’ phase have orthorhombic unit cell parameters of a = 1.30 nm, b = 2.22 nm and c = 3.36 nm with space group Pmc21, there are 4 chains in the unit cell and its density is 1.06g/cm3. In these crystals, the molecular backbone chains are packed parallel to the lamellar plane with the alky side chains vertical to lamella. Besides, the β’ phase spherocrystals were prepared by melt crystallization. The spherocrystals were composed of lamellar crystals, in which the backbone chains are packed parallel to the radius direction with the alky side chains normal to the substrates. Compared to the β phase, β’ phase is the thermal stable phase for F16. 2. For monodisperse PFO with 32 and 64 repeating units (F32 and F64, respectively), random thin films containing β phase were prepared by directly dropping from solution. Large-area continuous nanofibril thin films were prepared by melt crystallization. Crystalline films preserve some of texture characteristic of liquid crystalline films. There is lamellar structure in the crystalline films. The crystallization process undergoes radial growth from nucleus to form spherulite-like structure, moreover, to a certain extent, there is fusion at the boundary of spherulite-like structures. The crystalline films are α phase with orthogonal unit cell parameters of a = 2.60 nm, b = 2.38 nm and c = 3.32 nm. Compared to the β phase, α phase is the thermal stable phase for F32 and F64. 3. In the α phase nanofibril films of F32 and F64, the backbone chains are parallel to the width direction of nanofibrils with fluorenes stacking along the length direction. F32 and F64 remain extended in the nanofibrils. 4. The phase diagram of PFO with different chain lengths was obtained by summarizing above results. We found that the chain lengths can affect the melt-crystallized phases, the melt crystallization of F16 produces β’ phase, while for F32 and F64, it turns into α phase. The discipline of melt crystallization of PFO was summarized by comparing the morphology of these two phases. F16 tends to display the crystalline feature of micromolecule and produces typical lamellar crystals. Nevertheless, for F32 and F64, the characteristics of macromolecule are shown to form crystalline nanofibril films, but the films still represent the characteristic of lamellar structu

富勒烯胺基衍生物的选择性合成

富勒烯分子的发现使人们认识到了一个全新的碳材料世界，并立即引起了全世界科学家们的广泛关注，对富勒烯的研究热潮也由此拉开帷幕。富勒烯分子由于具有独特的三维空间结构和大π电子共轭体系，所以化学性质比平面的芳香族化合物更加丰富。自从C60能够被大规模的制备以来，科学家对富勒烯的研究不断深入，许多富勒烯衍生物在有机光电功能材料和生物医药等领域表现出了优异的性能。化学修饰一直是富勒烯的一个重要研究领域。在数目众多的富勒烯化学反应中，亲核反应，以其生成的产物结构易于控制、适用底物范围广，成为了富勒烯修饰中最常用的反应之一。为了满足富勒烯衍生物在各领域应用的需要，探索新的富勒烯化学反应以及合成具有特殊性质的富勒烯衍生物就成了研究的焦点。本论文重点研究了以单键连结的富勒烯二聚体为反应物，利用亲核反应，选择性合成 1,4-加成富勒烯胺基衍生物，主要研究内容如下： 以二聚体化合物PhCH2C60_C60CH2Ph为底物，利用亲核反应选择性合成单胺基化富勒烯衍生物1,4-(C6H5CH2) (NR2 )C60。通过具有强还原性的氢化钠拔去二级胺上的氢，生成胺基负离子亲核试剂。利用二聚体本身的空间位阻效应和特殊的电荷分布，当胺基负离子对二聚体PhCH2C60_C60CH2Ph进行亲核加成时，只能加成在苄基对位，产生1,4-加成结构衍生物。利用现场可见/近红外光谱对反应过程进行监测，提出了有别于与以往反应的反应机理, 结合理论化学计算研究了反应机理。利用二聚体与二级脂肪胺进行反应可以选择性得到单胺基化富勒烯衍生物，拓展了富勒烯与胺类化合物的反应。The discovery of fullerenes made people to realize a new world of carbon materials and attracted worldwide great attention. From then on, scientists show great interests in these cage-like molecules. Due to its unique three-dimensional structure and relatively free π-electron conjugated system, the chemical reactivity of fullerene is more plentiful than those planar aromatic compounds. Since the C60 became available in macroscopic quantities, the study of fullerene chemistry developed continuously. Many fullerene derivatives have exhibit excellent properties in the area of organic photoelectric material and biomedicine. The modification of fullerene is always an indispensable part in fullerene chemistry. Among various reactions, nucleophilic reaction is regarded as the most commonly used methods for functionalizing fullerene. This is due to its controllable products and extensive scope of substrates. In order to meet the needs of fullerene derivatives in various application area, explore the reactions of fullerene and synthesis of fullerene derivatives which have special property has became the focus of research. In this thesis, we have studied several nucleophilic reactions of singly bonded C60 dimers. By this method, 1,4-aminofullerenes could be regioselectively synthesized. The main works presented in this thesis are as the following: Taking single-bonded C60 dimers as starting materials, we could obtain 1,4-(C6H5CH2)(NR2)C60 selectively in one-pot through nucleophilic reaction. Anionic amine nucleophiles were produced as a result of reaction between NaH and secondary amine. Due to the effect of steric hindrance, only 1,4-addition pattern existed if nucleophilic attack reaction taken. Anionic amine can only attack at the para-carbon atom with respect to the benzyl. The reactions are monitored by in situ Vis–near IR spectroscopy, and possible mechanisms are proposed. Futhermore, the reaction mechanism were investigated by theoretical calculations.This is a novel mechanism which different from the traditional reaction. The preparation of monoamine functionalized fullerene derivatives are achieved via the reaction of PhCH2C60_C60CH2Ph and secondary amine. This work extends the chemical reaction of fullerene with amines

Side-Chain Engineering for Enhancing the Thermal Stability of Polymer Solar Cells

An effective strategy of engineering side chains is proposed for enhancing solar-cell-device thermal stability. As the conjugated length of the side chains increases, the morphological stability of the blend film is enhanced. The thermal stability of corresponding devices is consequently improved

Solvothermal synthesis of metal nanocrystals and their applications

Solvothermal synthesis has advanced significantly over the past decades and became a versatile approach to achieve the morphology control of well-defined metal nanostructures. This review covers the most recent progress on the solvothermal syntheses and applications of metal nanocrystals. Key synthetic factors are summarized, including temperature, reaction time, solvent effects, ligand effects, facet-specific capping agent effects, and reductant effects. The synthetic strategies, growth mechanism, and enhanced properties of metallic nanocrystals and multimetallic nanocrystals are introduced. The perspectives in the solvothernnal syntheses and applications of metal nanocrystals are discussed. (C) 2015 Elsevier Ltd. All rights reserved

Single-phased white-light-emitting Ca-4(PO4)(2)O:Ce3+,Eu2+ phosphors based on energy transfer

A novel single-composition Ca-4(PO4)(2)O:Ce3+,Eu2+ phosphor emitting white light was synthesized by conventional solid-state reaction for light-emitting diode applications. X-ray diffraction, photoluminescence spectra, and luminescence decay spectra were used to characterize the samples. Energy transfer from Ce3+ to Eu2+ ions was observed in the co-doped samples, and the transfer mechanism in the Ca-4(PO4)(2)O:Ce3+,Eu2+ phosphors was dipole-dipole interaction. The emission hue of Ca-4(PO4)(2)O:Ce3+,Eu2+ was found to vary from blue (0.165, 0.188) to white (0.332, 0.300) and eventually to orange (0.519, 0.366) by precisely controlling the ratio of Ce3+ to Eu2+. The combination of a 380 nm near-ultraviolet chip with a Ca-4(PO4)(2)O:0.02Ce(3+),0.012Eu(2+) phosphor produced a diode emitting white light with ultra-wideband emission and a correlated color temperature of 4124 K. Overall, results indicated that the prepared samples may be potentially applied in white-light-emitting diodes

Tumor Microenvironment Activated Photothermal Strategy for Precisely Controlled Ablation of Solid Tumors upon NIR Irradiation

Photothermal ablation has provided emerging and promising opportunities to further potentiate the efficacy of postoperative chemotherapy of tumor. However, it still cannot achieve a high level of selectivity because extraneous photodamage along the optical path to the tumor is unavoidable as the result of the uncontrollable distribution of the photothermal agents. In addition, it is technically difficult to keep photoirradiation localizing only on cancer cells. In this report, a new strategy is introduced for precisely controlled ablation of tumor through tumor microenvironment activated near-infrared (NIR) photothermal therapy. By taking advantage of the pH-dependent light-heat conversion property of Au@PANI nanoparticles, much higher photothermal effect at pH 6.5 than that at pH 7.4 is achieved. Therefore, in normal tissues and blood vessels, NIR irradiation cannot lead to a lethal temperature with little or no harm to normal cells. In contrast, in acidic tumor microenvironment, the photothermal effect is activated. Consequently, NIR irradiation can effectively kill cancer cells through local hyperthermia. Importantly, with the benefit of the internal and external control to switch on the photothermal ablation, the technical difficulty to precisely localize laser irradiation on tumor cells can be circumvented

Upconversion nanoprobes for efficiently in vitro imaging reactive oxygen species and in vivo diagnosing rheumatoid arthritis

Over-generation of reactive oxygen species (ROS) is closely associated with the biological processes of rheumatoid arthritis (RA). Thus, efficient monitoring ROS in inflammatory joints would be essential for better understanding the pathogenesis and optimizing therapeutic interventions. Herein, we designed a ratiometric nanoprobe utilizing upconversion nanoparticles (UCNPs) conjugated with chromophore labeled hyaluronic acid (HA) for high sensitively sensing ROS in the aqueous solution, bioimaging ROS in inflammatory mimic cells and diagnosing RA in vivo. In this approach, the conjugation of HA conferred UCNPs not only water solubility but also biocompatibility and ROS recognizing properties. Particularly, the HA backbone cleavage and detachment of chromophore labeled HA fragments from UCNPs induced by ROS inhibited the luminescent energy transfer (LRET) and allowed rational metric upconversion luminescence (UCL) emission as the detection signal. Importantly, the upconversion nanoprobe showed high effectiveness for early assessing the treatment response of arthritic animals to an antiarthritic drug-methotrexate (MTX). (C) 2014 Elsevier Ltd. All rights reserved

Synergistic effect of carbon fibers and carbon nanotubes on improving thermal stability and flame retardancy of polypropylene: a combination of a physical network and chemical crosslinking

Recently, an intensive research effort has been devoted to the fabrication of polymer composites with enhanced physical and chemical properties. In this work, the combination of carbon fibers (CFs) and carbon nanotubes (CNTs) was demonstrated to show a synergistic effect on improving the thermal stability and flame retardancy of polypropylene (PP). The results of morphology characterization indicated that both CFs and CNTs were well dispersed in the PP matrix. The temperature at the maximum weight loss rate of PP under an air atmosphere was dramatically increased by 93.4 degrees C, and the peak value of the heat release rate measured by a cone calorimeter was significantly reduced by 71.7%. The remarkably improved thermal stability and flame retardancy of PP were partially owing to the accelerated oxidation crosslinking reaction of PP radicals by CNTs (chemical effect), and partially to the in situ formation of a dense and continuous CF/CNT hybrid protective layer (physical effect). This was because the CF/CNT hybrid protective layer not only hindered the diffusion of oxygen into PP and the migration of volatile decomposition products out of PP, but also acted as a thermal shield for energy feedback from the flame

Multifunctional hollow CaF2:Yb3+/Er3+/Mn2+-poly(2-Aminoethyl methacrylate) microspheres for Pt(IV) pro-drug delivery and tri-modal imaging

Combining the multi-modal medical imaging with cancer therapy in one single system has attracted the great interests for theranostic purpose. In this paper, CaF2:Yb3+/Er3+/Mn2+-poly(2-Aminoethyl methacrylate) (UCHNs-PAMA) hybrid microspheres were successfully fabricated. The synthetic route to the nanocomposite based on a facile hydrothermal method for fabrication of hollow upconversion (DC) nanospheres at first and then post-filling the PAMA interiorly through photo-initiated polymerization. The UCHNs showed orange fluorescence under 980 nm near infrared (NIR) laser excitation, which provided the upconverting luminescence (UCL) imaging modality. Meanwhile, the presence of functional Mn2+ and Yb3+ offered the enhanced Ti-weighted magnetic resonance (MR) and computed tomography (CT) imaging, respectively. Thanks to introducing amine groups-containing PAMA inside the hollow nanospheres, the Pt(IV) pro-drug, c,c,t-Pt(NH3)2C12(00CCH2CH2COOH)2 (DSP), can be conveniently bonded on the polymer network to construct a nanoscale anti-cancer drug carrier. The UCHNs-PAMAPt(IV) nanocomposite shows effective inhibition for Hela cell line via KIT assay. In contrast, Pt(IV) pro-drug and UCHN5-PA1VIA microspheres behave little cytotoxicity to Hela cells. This should be attributed the fact that the anti-cancer ability can be recovered only when Pt(IV) pro-drug was reduced to Pt(II)-drug in cellular environment Furthermore, the in vivo experiments on small mice also confirm that the hybrid microspheres have relatively low toxic side effects and high tumor inhibition rate. These findings show that the multifunctional hybrid microspheres have potential to be used as UCL/MR/CT trimodal imaging contrast agent and anti-cancer drug carriers. 0 2015 Elsevier Ltd. All rights reserved